Dementia, a major cause of morbidity in the elderly, is characterized by cognitive and functional decline. Many clincal trials, targeted to improve the condition of demented patients typically focus on improving cognitive test scores, assuming that this outcome measure reflects an improvement in the disease. This assumption however has been challenged and there is a need to design studies to measure clinically meaningful improvement, such as functional independence. Another approach to the treatment of dementia is to intervene by treating those patients who are at risk for dementia. This requires an identification of factors which increase the likelihood of this disease. The specific aims of this study are: 1)To identify a non-demented population who are at-risk for dementia among the elderly within an urban community. The proposed population of elderly live in the multi-racial, multi-ethnic community of north Manhattan currently under study in the Washington Heights-Inwood Columbia Aging Project (WHICAP). 2)To conduct a double-blind parallel design placebo controlled clinical trial of l-deprenyl to maintain or improve function in this non-demented but at-risk population. There is significant evidence of catecholamine changes with age, particularly in monoaminergic systems. These biochemical systems may play a role in the functional deficits of aging. L-deprenyl, a monoamine oxidase-B inhibitor, is an agent that can improve neurotransmission in monoaminergic systems and has produced functional improvement in patients with Parkinson's Disease. 3)To use meaningful outcome measures to evaluate the ability of this pharmacological intervention to reduce the progression of loss of functional independence and dementia. Incident dementia is clearly a meaningful outcome in the non-demented individuals and a reduction in the number of individuals who become demented will be a measure of efficacy. Reduction of functional worsening will also be measured using currently accepted scales. Other outcome measures will consist of quality of life variables, instrumental activities of daily living and cognitive tests.